Location: Horticultural Crops Research2013 Annual Report
1a. Objectives (from AD-416):
Objective 1: Determine effects of water management on wine grape productivity and fruit maturity. Objective 2: Integrate the development and use of analytical methods for the evaluation of phenolic compounds and other chemical indicators of quality in fruit, fruit products, and wine. Objective 3: Determine effects of vineyard and vine microclimate on fruit development, vine productivity, and fruit quality, particularly phenolic compounds.
1b. Approach (from AD-416):
Our fundamental approach for conducting the proposed research is based on interdisciplinary work toward grape production systems and connecting production practices to the quality of the harvested fruit or value-added fruit products. Although each team member is responsible for a distinct experimental focus, overall goals and responsibilities of the contributors overlap because the interactions among system processes and properties transcend disciplines.
3. Progress Report:
A computer model was developed to alert grape growers to critically cold temperatures in winter that could damage their grapevines. This model was posted on a publicly accessible website operated by the cooperator, Washington State University. The model allowed growers to select a weather station closest to their own vineyards rather than from a central location at some distance from their farm, which was the main limiting factor of the previously available information. Because temperatures are different at different locations, it is important for the grower to know how cold it is expected to be overnight at his or her specific location. Damage to grapevines from excessively cold temperatures reduces grape yield in the following year. Temperature and sunlight affect the quality of grapes, which affects market price. Growers must manage grapevines to avoid excessive sunlight on the fruit which leads to excessive temperature; both are deleterious. We determined the negative effects of extreme high fruit temperatures. We also determined the effect of the range of temperature between day and night on the chemical compounds that impart astringency to wine. Wine grape producers in warm climates (the majority of the US industry) are applying these results to change the management of the shoots and leaves of the grapevines to provide some shade to the fruit during the hottest part of the day. During the past 5 years, selected preparation methods were employed for analyses on the relationship between agricultural practices (i.e., cover cropping and tilling, canopy leaf removal, vine nutrition), biotic stresses (i.e., virus status), and genotypes (i.e., black raspberry, lingonberry, cranberry, basil, potato) and their affect on fruit primary and secondary metabolites (i.e., proanthocyanidins, anthocyanidins, sugars, organic acids). In the new project plan (2013-2018), ARS scientists in Parma, Idaho, and Prosser, Washington, propose to refine agricultural management practices to be used by growers to improve fruit and fruit product quality, and to sustain a competitive US agricultural economy. An objective of this 5-year project was to enhance our understanding of how irrigation practices influence wine grape productivity and berry maturity. We identified influences of irrigation amount on vine canopy density, volatile compounds in grape and wine, and wine sensory attributes. We found an increased incidence of high temperature stress in deficit-irrigated vines grown under arid conditions with high solar radiation, particularly in west-exposed berries. In 2012 we completed a multi-year study showing that foliar application of a white, kaolin-based particle film to the vine canopy increased reflectance of solar radiation from leaf and berry surfaces and beneficially reduced surface temperatures. In 2012, we collected the second year of a multi-year study on the influence of irrigation amount and frequency on vine water status and productivity. Our replacement project will continue to study irrigation practices and techniques that optimize productivity and fruit quality and mitigate the impact of drought and cold.
1. To remove or not to remove? ‘Pinot noir’ grapes are a high valued crop in Oregon. Canopy leaf removal, which is a commonly used canopy management tool was evaluated in this study. Oregon growers start removing leaves anytime between fruit set and véraison with the assumption that it will improve microclimate around the cluster, prevent pest incident/severity, improve spray permeation, reduce amount of pesticide used, etc., although there are direct and indirect consequences on vine growth and berry quality due to this practice. ARS scientist in Parma, Idaho, and Oregon State University collaborators were the first to demonstrate that if Oregon winegrape growers desire to reach high berry pigment levels, they should remove leaves at bloom and maintain a free leaf zone up until harvest. Other fruit maturity indices were not altered by early leaf removal.
2. Phenolic quality of cranberry dietary supplements. Cranberry products have the potential to be used as a remedy or to prevent urinary tract infections (UTIs). ARS scientist in Parma, Idaho, examined five commonly used cranberry sample purification methods prior to phytochemical analysis. The current available commercial cranberry products were eleven-fold different in proanthocyanidin content, the compound that might possibly prevent UTIs. During this investigation, a cranberry juice cocktail product was discovered that contained a red pigment not originating from cranberry fruit. It is possible that some commercial cranberry products may not be useful in relieving or preventing UTIs depending on proanthocyanidin content.
3. Relationships between agricultural practices and phytochemicals. Anthocyanins, natural pigments that contribute to color and taste in wine-grapes, are essential quality constituents. ARS scientists in Parma, Idaho, and Davis, California, explored how two rootstocks (110R and 420A) and three vineyard floor management techniques (1- resident vegetation that was tilled, 2- barley planted then mowed, and 3- barley planted then tilled) affected ‘Cabernet Sauvignon’ grape anthocyanin content and composition. Research vineyard was located in California, USA. Mowing the vineyard floor can be used as an additional management technique to increase grape color. As mowing for weed control is a sustainable agricultural practice, it has the added benefit of improved air and water quality compared to the dust and runoff from traditional tilling.
4. The daily pattern of high temperature affects grape quality. An ARS researcher at Prosser, Washington, with collaborators at Oregon State University addressed the problem of how temperature affects the compounds in grapes that are responsible for astringency in wine. We determined that it is not high temperature per se that affects these compounds but the size of the difference between high daytime and low nighttime temperatures that has greatest effect. The potential impact for grape growers in warm climates is to adjust the management of the vines' shoots and leaves to provide some shade to the fruit during the hottest part of the day.
5. A web-based cold temperature prediction system was developed for grape growers. An ARS researcher at Prosser, Washington, in collaboration with Washington State University addressed the problem of a lack of vineyard-specific temperature warnings in winter for grape growers whose crops may be damaged by extreme cold. A computer model that used historical data was built to take current temperatures and predict the likelihood of winter damage to several varieties of grapevines in the Pacific Northwest. Nightly information about critical temperatures allows growers to decide whether they need to enact expensive frost-protection measures on any given night. Nightly knowledge that temperatures are not expected to dip below critical values save growers time and expense in protecting their vineyards for the following growing season.
6. Coating wine grape leaves mitigated high temperature stress in deficit-irrigated vines. Wine grapes in arid regions are often irrigated with amounts of water that beneficially restrict vegetative growth but adversely increase leaf and berry surface temperatures. ARS researchers at the worksite in Parma, Idaho, found that a white film coating on the leaves of the vine canopy increased the reflectance of solar radiation and that the resulting decrease in leaf and berry surface temperatures beneficially increased leaf gas exchange and berry color. Sensory panelists were unable to detect a difference in taste between wines produced from vines that were or were not coated with the particle film. The published results from this research can be used by growers in arid regions with high solar radiation to mitigate high temperature stress in wine grape.Lee, J., Skinkis, P.A. 2013. Oregon 'Pinot noir' grape anthocyanin enhancement by early leaf removal. Food Chemistry. 139:893-901.